Ryo Kurihara

The specific surface areas of sealed-cured hardened cement pastes (HCP) were evaluated during the hydration process using three types of Portland cement and with two different water-to-cement ratios. The BET surface area was measured by water vapor/nitrogen sorption and directly compared with that obtained by the fast exchange model measured by 1H NMR relaxometry. The results confirmed that the total surface area evaluated by 1H NMR was consistently 2–2.5 times larger than the water vapor BET su

We achieved CO 2 electroreduction to C 2+ products ( j C 2+ = 0.7 A cm −2 ) in aqueous electrolytes containing tetramethylammonium cations without alkali metals. Smaller cations enhance the electric field in the double layer, promoting C 2+ formation.

Calcium silicate hydrate (C-S-H) is the primary hydration product of modern Portland cement pastes and concrete. Concrete is inevitably dried and rehumidified when it is hardened with water, for operation under ambient conditions. This drying and rehumidification induces a change in the microstructure of the C-S-H agglomerate and is considered the driving factor of anomalous moisture transport in cement pastes. To obtain further insights into the microstructural changes in C-S-H in response to d

Abstract The synthesis of multi‐carbon products (C 2+ ) by electrochemical CO 2 reduction reaction (CO 2 RR) is a promising technology that will contribute to the realization of a carbon‐neutral society. In particular, efficient CO 2 RR to produce C 2+ in acidic electrolytes is desirable because the conversion of CO 2 to inert (bi)carbonate can be suppressed under acidic conditions, thereby increasing the efficiency of substrate CO 2 utilization. Herein, since C 2+ products are produced via the

This paper reports the influence of nano-TiO2 on hydration reactions and drying shrinkage behavior during the first drying process of hardened cement pastes. Cement pastes containing 3 wt% nano-TiO2 (by external addition) in cement and reference samples were prepared with water to cement ratios (W/C) of 0.40 and 0.55. The results of experiments on samples hydrated for 6 months show that in the mature state of hydration, the addition of TiO2 retards the reaction of belite and slightly reduces the

収縮低減剤（SRA）の作用機構は、過去の研究では気液界面の表面張力の低下によって同一湿度における含水率が小さくなり、毛細管張力機構における含水率の低下により乾燥収縮が低減されると説明されている。本研究ではSRAの使用濃度および異なる湿度乾燥下での長さ変化と質量変化の測定を行い、SRAの作用機構に関する考察を行った。その結果、SRAによる収縮低減効果は、毛細管凝縮の起こらない低湿度域においても、SRAの使用濃度への依存性をもって発揮された。また、SRAの作用機構は、毛細管張力機構における表面張力の低下のみによるものではなく、別の機構を含んだものであることが確認された。